Casualties

Book: Unknown, but likely moderate

Complete destruction of the Dark LordSauron, Barad-dûr and its inhabitants, all Nazgûl, the Mouth of Sauron (film only), nearly all of the Easterlings and Southrons killed with an unknown number surrendered. Numerous Orcs slain or fled. Not one evil creature survives.

"We have not the Ring. … Without it we cannot by force defeat his force. But we must at all costs keep his Eye from his true peril. We cannot achieve victory by arms, but by arms we can give the Ring-bearer his only chance, frail though it be. … We must push Sauron to his last throw. We must call out his hidden strength, so that he shall empty his land. We must march out to meet him at once. We must make ourselves the bait, though his jaws should close on us. … We must walk open-eyed into that trap, with courage, but small hope for ourselves."

The Battle of the Black Gate, also known as the Battle of the Morannon, was the final major battle of the War of the Ring. It resulted in the ultimate defeat of Sauron not by victory on the battlefield, but by means of the destruction of the One Ring by the hobbit Frodo.

After the Last Debate, the Men of the West assembled the Host of the West, 10,000 strong, led by Aragorn, who marched on the Black Gate as a diversionary feint to distract Sauron's attention from Frodo and Sam, who were carrying the One Ring through Mordor to be destroyed in the fires of Mount Doom. It was hoped that Sauron would think Aragorn had the Ring and was now trying to use it to overthrow him in Mordor.

Initially, the Host of the West consisted of 10,000 men, but 3,000 Rohirrim were sent to guard the crossroads, leaving Aragorn with 7,000 men. Before they reached Ithilien they were ambushed by Haradrim and Easterlings, but they drove them away easily with no casualties.

Then, as they approached Dagorlad, some of the farmers of Lossarnach and Rohan were too afraid to continue to pass the Desolation of the Black Gate. Aragorn dismissed the faint-hearted, ordering them to liberate Cair Andros on the riverAnduin. This resulted in the departure of an estimated 1000 men, leaving Aragorn with 6,000.

Before the battle began, the Black Gate opened slightly, letting out a small embassy. At the head was a high servant of Sauron, a Black Númenórean called the Mouth of Sauron, who had been ordered to speak with the Captains of the West. He reasoned that the Army of the West could not defeat Sauron's host on the battlefield, and demanded the Army surrender. The Lieutenant then brought forth several items that had belonged to Frodo and Sam (Sam's sword, an Elven cloak, and Frodo's Mithril shirt). Gandalf asked for the terms of their surrender, which were to allow Sauron dominion over Isengard and Rohan, as well as Gondor's vassalage. Gandalf vehemently refused.

Realizing the Army intended to fight and being outnumbered, fear and anger overcame the Lieutenant, and he retreated to the Black Gate, which then opened to reveal a massive army of Sauron's forces. Thousands of Orcs also emerged from the hillsides around the Black Gate. In the film Aragorn, not believing what happened to Frodo, beheads The Mouth of Sauron.

Against the Host of the West was arrayed a large hordes of Orcs, Trolls, and Mannish allies such as the Easterlings and Haradrim. An exact count is not given of the number of Sauron's forces, but it is said that they were "ten times and more than ten times" greater than the Host of the West, making it a force of at least 60,000. Sauron's forces surrounded the Armies of the West on three sides, with the Easterlings on the left flank, the Orcs held the center, and the Haradrim on the right. Initially, Sauron's forces found difficulty in getting to the Army of the West, due to the large slag pools and pits of waste surrounding parts of the Black Gate, which impeded their progress. The Armies of the West always had cohesive stability within their center and kept the Enemy from breaking through by force of numbers. The solid infantry squares of Gondor infantry beat off their inferior Orcish opponents while the Rohirrim cavalrymen staved off the archers of the Harad. The small force of Easterlings launched a quick attack before being repulsed by the armies of Gondor and Rohirrim while the larger Haradrim force slowly retreated to the hills. By now, pressure had eased off of the flanks of the Armies of the West, who smashed into the lines of the Orc-host, slowly beating them off and forcing a retreat back through the Black Gate (though not without suffering sizable losses of their own).

During the course of the battle, the remaining eight Nazgûl emerged and attacked the Army of the West. Shortly thereafter, however, the Great Eagles of the Misty Mountains, led by Gwaihir the Windlord, arrived and attacked the Ringwraiths, preventing them from pressing their aerial advantage. Trolls began to crash through the lines of infantry, and the Orcs and Easterlings made renewed assaults on the Army of the West, encircling it. Many of the soldiers of the West began to become distraught. That was when Frodo put on the One Ring and Sauron realized that Frodo and the Ring were inside Mount Doom.

The Nazgûl immediately left the battle to intercept Frodo. Before they could get there however, Gollum bit the Ring off Frodo's finger and danced with joy accidentally falling into the Crack of Doom, destroying the Ring, and Sauron's power was overthrown.

Aragorn leads the army of the West as he charges into battle.

Barad-dûr, the Black Gate, and the Towers of the Teeth collapsed to ruin. The Orcs and other creatures of Sauron were completely directionless with the Dark Lord's demise and were easily defeated and destroyed by the remaining troops of the Host of the West. Some of the Easterlings and Haradrim fought on stalwartly, though eventually many threw down their weapons and surrendered (later to be sent home in peace by Aragorn).

Despite the destruction of Mordor and its armies, the fight against Sauron's remaining forces would continue in the northern theater of the War of the Ring for several weeks, notably at Dol Guldur in Mirkwood and at The Lonely Mountain, but the power of Sauron, the Dark Lord of Mordor, was no more.

In the Rankin-Bass version of The Return of the King, Aragorn, now in full command of Gondor's armies, chooses to march on the Black Gate despite the odds. When Aragorn comes to the Black Gate, he calls on the Dark Lord to come forth and "atone for his evils" and depart these lands. The gate opens and the Mouth of Sauron comes out and refutes his demands in an insulting manner. Aragorn refuses to even acknowledge him and dismisses him as merely one of Sauron's slaves angering the Mouth. The Mouth rides away laughing in an evil manner. (The Return of the King (1980 film))

In Peter Jackson's The Return of the King the Slag Hills are absent, as is Imrahil. The confrontation with the Mouth of Sauron was cut, though in the extended edition of the film it was put back in, but with Aragorn decapitating the Mouth of Sauron in anger (in the book the Mouth of Sauron rode back to Cirith Gorgor).

In Jackson's version, the Dark Lieutenant is portrayed as the "Mouth of Sauron", a disfigured emissary rather than a soldier. The Mouth at first seems angered by what Gandalf says, but then regains his stature and speaks in a mock-friendly manner, calling him "Old Greybeard". He tells Gandalf that he has "a token he was bidden to show" and then takes out Frodo's mithril vest and throws it at Gandalf. He seems to be getting enjoyment out of seeing the shocked and horrified faces of Frodo's friends. Seeking to hurt Gandalf even more, he begins lying about how Frodo suffered greatly before dying, and smiles when a tear runs down Gandalf's face.

At this, Aragorn approaches on his horse. The Mouth of Sauron seems spiteful towards Aragorn, saying that "It takes more to make a king than a broken elvish blade". He's then beheaded by Aragorn, an action which shocks Gimli, causing him to say sarcastically, "Well, I guess that concludes negotiations!" Aragorn then turns around, saying he does not believe that Frodo is dead. At this point, Sauron's eye moves towards the Black Gate. The Mouth of Sauron's death was never shown in the book, but rather left his fate unknown.

Originally, Aragorn was going to fight Sauron, who was to appear in a bright blinding light in the form of Annatar, and then was to turn into the armored Sauron from the prologue of the first film, at which Aragorn and Sauron would begin to duel. This idea was later dropped to stay more consistent with the battle in the novel; instead Aragorn fights a troll in the film, using the same choreography as the Sauron fight, but with a Troll replacing Sauron via CGI. In another difference from the book, Merry fights in the battle, while in the book he remained in Gondor.

In the movie, during the last debate Gandalf makes it clear that there are a force of ten thousand Orcs at the Black Gate, but the army of Men of the West is still unknown, possibly 500 because when one looks at the circle, the Men of the West seem to have about 500 men. The battle starts after Aragorn killing the mouth of Sauron. He gives an epic speech to the small force of men then gets off his horse and they prepare for battle:

"Sons of Gondor! Of Rohan! My brothers! I see in your eyes the same fear that would take the heart of me. A day may come when the courage of Men fails, when we forsake our friends and break all bonds of fellowship, but it is not this day. An hour of wolves and shattered shields when the age of men comes crashing down, but it is not this day! This day we fight! By all that you hold dear good on this earth, I bid you stand, Men of the West!

A force of 10,000 Orcs surround the Men of the West who after having Aragorn run towards the enemy lines charge bravely into the Orcs. Despite having only about 300 soldiers of Gondor and 200 Rohirrim they kill many Orcs while sustaining light casualties, although it later becomes clear that unless the Ring is destroyed they will be completely wiped out as their casualties start getting heavy. When Aragorn is being stepped on by a troll the One Ring is destroyed and the forces of Mordor were almost completely destroyed with only a few hundred fleeing (the aforementioned troll being one of the first to take flight. The Lord of the Rings: The Return of the King (2003)